metadiary is a quick and easy to use diary.
metadiary is designed so you can easily tag your calendar with your activities, and then it helps you to understand how much time you spend on them, and eventually to reorganize them.
The program is still in an early development stage, there are many features which could be added and there may be some bugs in the code, but it is already usable on GNU/Linux and Windows.
You can find some screenshots of the program in the project page at sourceforge: http://sourceforge.net/projects/metadiary.
You can download metadiary from: <http://sourceforge.net/projects/metadiary/files>.
The development area is located at: <http://sourceforge.net/projects/metadiary>.